Repeated NOT
Applies to ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
The NOT unary operator reverses itself, when called repeatedly, meaning that redundant NOT operators can be removed.
Using Settings.transformPatternsNotNot, the following transformations can be achieved:
-- With Settings.transformPatternsNotNot active, this: SELECT NOT (NOT (x = 1)), NOT (NOT (NOT (x = 1))) FROM tab; -- ... is transformed into the equivalent expression: SELECT x = 1, -- NOT (NOT (x = 1)) NOT (x = 1), -- NOT (NOT (NOT (x = 1))) FROM tab;
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